Shortly before his death in 1989, Ayatollah Khomeini, Iran’s spiritual leader, sent a delegation to make the request to the then Soviet president, Mikhail Gorbachev.

Details of communications between the two countries are included in top secret diplomatic documents unearthed by Exaro from a huge Soviet archive that has been smuggled to the West. Exaro has had some of the material translated from Russian to English.

A note taken at a Politburo meeting in January 1989 by Vadim Medvedev, who was secretary of the central committee of the Communist Party of the Soviet Union, reads: “Results of talks between Gorbachev and the personal envoy of Imam Khomeini. In a personal message, Imam calls on us to abandon Marxism-Leninism in favour of Islam.”

“Gorbachev (laughed at length before he starts speaking): ‘He suggested that we should destroy communism!’”

According to the transcript, Gorbachev continued: “Everybody wants Iran: Western Europe keeps its position there (especially France and Germany). In Iran, a lot people are looking for a way out of fundamentalism. They are waiting for the right time. They seek our support to oppose the pressure from the West.

“‘Khomeini’s message is a very important signal. The woman who brought it was all covered from top to bottom; I could only see her glasses. I held out my hand, and she took it.’”

“The message is not just a signal, it is a political sign, meaning, ‘Let’s co-operate and look for new opportunities.’”

“We need to give the Imam a reply although we should not get involved in a discussion about Islam. The message is hand-written. Our specialists might help me to formulate my response. We have knowledgeable people, including Muslims. They know what to do in such cases. Maybe we should send someone to Iran?”

The transcript of the Iranian delegation’s meeting with Gorbachev records the Soviet leader’s reaction to Khomeini’s invitation to turn to Islam. He said: “I do not share the Imam’s bleak assessment of socialism and communism. Nor can I accept the role of a destroyer of communism, which he assigns to the general secretary [of the Communist Party] and the chairman of the Presidium of the Supreme Soviet.” Gorbachev was referring to posts that he occupied at the time.

He continued: “I have to disappoint the Imam: together with my associates, we see our goal as fully restoring the values of socialism and Marxist doctrine. This doctrine incorporated the best achievements of what the human mind has produced.

“It is not divorced from the general culture of mankind. We want all the achievements of civilisation to be used in the name of establishing common values and in the interests of the world community.”

Khomeini, according to material from the archive, was disappointed with Gorbachev’s reply and his reluctance to discuss Islam.

Documents providing insight into the relationship between the USSR and Iran are revealed in a book, ‘Behind the Desert Storm’, due to be published next month.

They also show how the Soviets supported an attempt by Syria’s then president, the late Hafez Assad, to forge a closer alliance against Israel with Iran, despite its bitter conflict with Iraq.

Other documents from the archive give more insight into Soviet-Iranian relations, which evolved from hostility to an alliance during the final years of the USSR.

Exaro revealed documents from the same archive last month that showed how America secretly took part in an audacious Soviet plan to strike a peace deal with Saddam Hussein, then Iraq’s president, that would have stopped the outbreak of the Gulf War of 1990-1991.

Pavel Stroilov is a Russian journalist and political exile living in London, and author of ‘Behind the Desert Storm’. Additional reporting by Fiona O’Cleirigh.